Inkjet printers, i.e., printers which form an image by firing a plurality of discrete drops of ink from one or more nozzles on to the surface of a recording sheet placed adjacent the nozzles, have recently enjoyed a large increase in sales. Modern inkjet printers can print on almost any conventional paper or similar medium. The quality of images produced by such printers is greatly affected by the properties of the medium used. More particularly, to produce high quality images reliably, it is necessary that the recording medium, i.e., the inkjet recording sheet, dry rapidly, not promote excessive spreading of the ink droplet, not promote “wicking”, that is spreading of ink by capillary action through fibrous medium such as paper, and, importantly, be such that the contrast of the dried image with moist surfaces does not result in bleeding of ink from the image.
In U.S. Pat. No. 6,933,024, T. Chen describes the use and preparation of poly(vinylpyrrolidone-(PVP) co-vinylalcohol) as an inkjet recording material by hydrolyzing PVP/polyvinylacetate copolymer. However, the resultant hydrolyzed product was not hydrophobic, i.e., water resistant.
In U.S. Pat. No. 4,350,788, W. Shinokawa et al. describes a synthetic resin emulsion containing an acetoacetylated polyvinyl alcohol as a protective colloid for use as an adhesive, paper treating agent, paint, fiber and textile treating agent and cement modifier. However, such a product would not be practical as an inkjet medium.
In U.S. Pat. No. 2,536,980, G. Jones describes synthetic polyvinyl alcohol-1-butene-1,3-dione reaction products and processes. However, the patent does not disclose applicant's hydrophobic, cross-linkable acetoacetylated lactam/vinyl alcohol copolymers.
Accordingly, it is an object of this invention to provide an improved inkjet recording medium. Another object herein is to provide a hydrophobic crosslinkable acetoacetylated lactam/vinyl alcohol copolymer.
Still another object of this invention is to provide a copolymer which is made by partially hydrolyzing a polyvinylpyrrolidone/vinyl acetate copolymer to produce a poly(vinylpyrrolidone/vinyl alcohol) copolymer and then acetoacetylating the copolymer with a diketene to obtain said desired copolymer.
These and other objects and features of the invention will be made apparent from the following description.